Multiplex picture projection apparatus



S. DOMESHEK MULTIPLEX PICTURE PROJECTION APPARATUS Nov. 24, 1953 2 sheets-sheet 1 Filed Dec. 16, 1949 INVENTOR. JOL' Dom-SHEA ATTORNEY Nov, 24, 1953 s. DOMESHEK 2,660,087

MULTIPLI-:X PICTURE PROJECTION APPARATUS Filed Dec. 16. 1949 2 Sheets-Sheet 2 D JNVENTOR. 501. oMEsHEK Patented Nov. 24, i953 UiD S MULTIPIJEX 'PICTURE PROJECTION APPARATUS Sol Domeshek, Great Neck, N. Y.

Application December 16, 1949, SerialfNm 133,454

(Cl. y,GSi-1615) (Granted Aunder Title 35, IJ. ;S.. Code 11952),

sec. 266;)

11 Claims.

indicatoi` reflectoscope) navigation techniques to 4 groups of students. Such navigation involves the optical superposition some form of chart upon a radar PPE (plan position indicator) yand the maintenance of the two images Yin as near perfect registry as possible, thus allowing the center of the PPI representing the craft to determine its own position on the chart. Thus, for group demonstration, the two images must be projected .upon a screen with their axes of proiection co.- incident.

Such uni-axial .duo-projection has been 'accomr plished in the past by use of partial-silvered Ymirrors or prisms, but such systems have had serious disadvantages. First, ,dissipation of 60% or more .of the initial light energy 0f .the .projectors, resulting in inordinately high operating temperatures, shorter operating life for the equipment, and discomfortto the operator, were characteristic. Second, magnification was limited by the low degree of .brilliance of the images. Third, in systems using .only approximate coaxial projection to achieve the `applications Anoted above, oblique reflection introduces astigmatism. The structure herein disclosed `and claimed over- ,comes these disadvantages.

The primary object of the invention is to vprovide uni-axial duo-projection .apparatus .adapted to make efficient use of the initial light energy of the projectors, thereby assuring lower operating temperatures and longer operating life, providing greater operator convenience, producing more brilliant images and thus permitting greater magnication, longer throw upon a screen and operation in rooms lit normally.

Another object is to provide uni-axial duoprojection apparatus employing a multi-prism mirror as the axis-combining element and positive .spherical lenses ,and plane mirrors to :direct .the dual axes upon the combining element.

A further object is to provide uni-axial duoprojection apparatus incorporating a positive cylindrical lens to eliminate astigmatism due .to oblique reflection.

Other yobjects 'and man-y of the attendant radvantages .of this invention will be readily appreciated as the same becomes better understood py reference to the following detailed description when Yconsidered. in connection with the Sacconipanying drawings wherein:

Fig. 1 isa plan viewoli uni-axial duo-proiection apparatus, showing a preferred embodiment of the invention;

Fig. V2 is a diagrammatic View thereof;

Pig. "3 a section taken on :the line 'ii- .3 .of

Fig. 1;

Fig. 4 is a .section -taken :on the line '1l-# of Fie. l;

Fig. v5 is Va section taken von -the line 5-.5 of Fig. l;

Fig. l6 :is a 'section taken .on the vline .ef-.6 V:oi

Fig. 7 is a section taken on the line *li-. i of Fig. 41; and

Fig. .8 is a section taken on .the line :8e-8 Yof Fig. 1.

Similar numerals refer -to similar parts throughout the several views.

.General torrangcment As illustrated 'diagrammatically in Fig. 2, the divergent beam from the left projector A is converted into a parallel beam bythe positive spherical lens B that is placed in its path. `'This parallel ybeam is then deflected to the right by a plane mirror C that is set at 66 to the axis of the beam toward a multi-prism mirror D. The base line of mirror D is normal to fthe original projection axis, and the vertical faces of said Amirror l) alternately lie parallel to the plane deflection mirror-G and atja '60 angle to said mirror C.

This arrangement causes the parallel 'beam to strike only `those faces of the multi-prism mirror D that are parallel to the plane mirror C and to v-be reilected ltotally Lalong a path para-llel to its' original path. However, since =the parallel beam has now suier'ed a horizontal astigmatism because it has undergone `an oblique rellection, a positive spherical lens E is ernployed to reconvert the parallel beam to a convergeht one, and a positive cylindrical lens F having Aa vertical axis -is incorporated in the system to correct such Vhorizontal astigmatism. Thus, an image originating at projector A as a circle will hit the screen G as a circle.

Similarly, the divergent beam from the right projector H is converted into a parallel beam by the positive spherical lens J that is placed in its path. This parallel beam is then defiected to the left by a plane mirror K that is set at 60 to the axis of the beam toward mirror D. IThe base line of said mirror D is normal to the original projection axis, thus causing the parallel beam to strike only those faces of said mirror D that are parallel to the plane mirror K and to be reflected totally along a path parallel to its original path. Correction for horizontal astigmatism is then effected in the manner described with reference to the beam from the left projector.

Coincident axes of projection and accurate registry of the two images on the screen is achieved by providing a frame support including means to adjust the distance between the projectors A and H and by providing distance control devices to vary the positions of lenses B and J, mirrors C and K, mirror D, and. lenses E and F.

Frame support and distance control 'mechants Projector standard l! is a beam having a medial arm portion i3 and an upstanding flange l5 located at the end of said arm portion. A. plurality of posts ll welded to said standard il carry a tube l that serves as amain guide rail and support for the projector platforms 2i and 22. A pair of posts i5 welded on said arm portion i3 carry rotatably a turnbuckie '25, said turnbuckle being disposed parallel to said tube l. Oppositely threaded shafts 2 and 2Q are secured in opposite ends of said turnbuclrle, said shafts extending'parallel to said tube le.

Projector platforms 2i and 22 are plate members each adapted to serve as a base for a standard motion picture projector. Each of said platforms is provided with a depending flange portion 3|. Brackets 33 secured to the nether face of each of said platforms mount rollers 35, which ride on tube I9. Brackets 3l, also secured to the nether face of each of said platforms, are vprovided with threaded bores 39 that receive the threaded shafts 2l' and 25. These elements are connected in such a manner that the platforms 2l and 22 are carried equidistant from an axis normal to tube i9, and are moved simultaneously and equidistantly towards or away from such axis by rotation of turnbuckle 25.

Channel beam il, provided with lightening holes 53, is positioned parallel to tube I9. Y Multiprism mirror mount @-5 is a plate secured at the mid-point of said beam @l by bolts dl and nuts 58. Rods 39 have their threaded ends secured to ange l5 by nuts 5l and extend slidably through bores 55 in said mount Q5. Threaded rod 55 has its end secured to flange l5 by nut 57 and extends slidably through bore 5e in said mount 45. Said rod 55 carries nuts (il fore and aft said mount 5 to secure said mount and the channel beam ll at a selected distance from tube Converging-beam-lens support 53 is a plate member carried slidably on rods Q9 and 55a, beyond mount 55, and nuts 55 carried on rod 55 fore and aft said support 63 are provided to secure support G3 at a selected distance beyond mount 135.

Cylindricallens support 5l is a plate member carried slidably on rods 49 and 55, beyond support 53, and nuts 5S carried on rod 55 fore and aft said support di are provided to secure support 5'! at a selected distance beyond support 63.

Von supports 'l1 by posts 99.

Said rods i9 and 55 terminate beyond support 3? in bracket ll, which is carried on shoe 13. Rods i9 are secured in said bracket, and rod 55 extends therethrough, being secured by nut i5.

Parallel beam lens support 'il' is a plate member carried slidably on rods '59, which extend through bores 8f3 in said support Ti and have their threaded ends secured to depending flange portion 3| by nuts 5|. Said rods A553 bear on channel beam lll, and are slidable relative said beam, both fore and aft and along the length of said beam. Threaded rods @il have their ends secured to said flange portion 3| by nuts 35 and extend slidably through bores 8'! in said support i?. Said rods 83 carry nuts Se fore and aft said support 'if to secure said supports at a selected distance from tube I9.

Plane mirror supports 9i are plate members carried slidably on rods 19 and 83, beyond support ll, and nuts 93 carried on rods 33 fore and aft said supports 9| are provided to Asecure supports 9i at a selected distance beyond support 1l.

Rods 19 have their ends capped beyond supports 9| by brackets 95, and rods 83 pass through said brackets and are secured thereto by nuts Sl.

From the foregoing description, it is apparent that shafts 21 and 29 and beam 4l are maintained parallel, and that rods 49, 55, 79 and 83 are maintained parallel and normal to shafts 2'! and 29 and beam M. It is further apparent that the projector platform 2| and its associated supports 'Il and Sl, and the projector platform 22 and its associated supports 11 and 9| can be moved towards or away from the axis defined by rod 55, each unit being maintained equidistant therefrom, and that mount 45 and supports 53, 67, l1 and Sl can each be adiusted fore and aft and secured in adjusted position.

The optical system tion, the plane mirrors of the system are oriented at 60 to the projection axes, and the faces of the multi-prism mirror are parallel alternately to eachof the plane mirrors, as shown in Figs, 1 and 2.

Positive spherical lenses B and J are mounted Said lenses preferably are coated to minimize surface reflections and increase overall light transmission.

Plane mirrors C and K are mounted on supports 9i, being secured thereon by screws till. Said mirrors preferably are front surfaced and have a coating that will protect that surface from corrosion due to atmosphere and fingerprints, and will also aord protection from minor abras1on.

Multi-prism mirror D is mounted on the prismatic mirror mount 45, being secured thereon by screws |03. Vertical faces |55 of said mirror D are parallel to mirror C, and alternate vertical faces Ill'l of said mirror D are parallel to mirror K. Said mirror D preferably is front surfaced and provided with a protective coating similar to that of the plane mirrors C and K.

Positive spherical lens E is mounted on support y(ft by post E05. Said lens E preferably is coated to increase light transmission.

The cylindrical surfaced positive lens F is mounted on support 61 by post IIJ'I, and preferably is also coated. Said lens F is of such focal length as to neutralize the horizontal astigmatism introduced by the multi-prism mirror.

In operation, projectors A and are seated Orl projector platforms 2| and 22 respectively. The divergent beam from projector A is converted into a parallel beam by the positive spherical lens B, the parallel beam being obtained by fore or aft adjustment of support .11. This parallel beam is then defiected to the right by plane mirror C, which is set at 60 to the axis of the beam, toward multi-prism mirror D. Since the base line of mirror D is normal to the original projection axis and since the vertical faces |05 and lill of mirror D are alternately parallel to the plane deflection mirror C and alternately at a 60 angle with mirror C, the beam is reflected by mirror C along a path parallel to its original path. The beam strikes only faces |05, which are parallel to the plane mirror, and are thus totally refiected along a path parallel to the original path of said beam.

The parallel beam having ,suffered a horizontal astigmatism because it has undergone an oblique reiiection, it is then passed through positive spherical lens E, Which reconverts the parallel beam to a. convergent one, and then through a positive cylindrical lens with a vertical axis, lens F, so that horizontal astigmatism is corrected.

In similar fashion the divergent beam from projector H can be traced through the systemthrough lens J to mirror K, then to faces 107 of mirror D and then through lenses E and F. It is apparent that coincident axes of projection and accurate registry of the two images on the screen can be achieved merely by properly adjusting the perpendicular distance between the two Vprojectors by means of turnbuckle and visually-observing the images merge into one on the screen.

In one particular application of the system, one of the projectors is equipped with X 'and Y motion cranks acting upon a member in the focal plane of the projection lens carrying the chartlet and the other projector shoots a picture of the radar PPI. With such a device, an entire class can observe and be instructed in the techniques of VPE, navigation.

It is also to be noted that the light loss of the system is only that resulting from absorption in the various glass surfaces, and is of the order of 15%, Whereas co-axial systems heretofore employed are characterized by light losses of the order of 60% Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that Within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes Without the payment of any royalties thereon or therefor.

I claim:

l. An optical system comprising a projector adapted to deliver a rst beam of light rays, a second projector adapted to deliver a second beam of light rays parallel to said first beam, mirrors in the path of each of said beams faced to direct the beams reflected therefrom toward each other, and a multiprism mirror having alternate faces parallel respectively with said mirrors and in the path of the reflected beams.

2. An optical system comprising a projector adapted to deliver a first beam of light rays, a second projector adapted to deliver a second beam of light rays parallel to said first beam, mirrors in the path of each of said beams faced to direct the beams reflected therefrom toward each other, a multiprism mirror having alternate faces parallel respectively With said mirrors and in the path of the reflected beams, and means in the path of the last mentioned beams for correcting astigmatism.

3. optical system comprising a projector adapted to deliver a Afirst beam of light rays, a

second projector adapted to deliver a second beam of light rays parallel to said first beam, mirrorsv in the path of each of said beams faced t0 direct the bea-ms reflected therefrom toward each other, a multiprism mirror having alternate faces parallel respectively with said mirrors and in the path of the reflected beams, means in the,

path of the beams that have been reflected from the multiprism mirror t0 convert the parallel beams into convergent beams, and means in the path of the last .mentioned beams for correcting astigmatism.

4. An optical system comprising a projector adapted to deliver a first beam of divergent light rays, means to convert said light rays to a first beam of parallel light rays, a second projector adapted to deliver a second beam of divergent light rays, means to convert said light rays to. a second beam of parallel light rays parallel to said firstY beam, mirrors in the path of each of said beams faced to direct the beams reflected therefrom toward each other, and a multiprism mirror having alternate faces parallel respectivelyl With said mirrors and in the path of the reflected beams,

5. optical system comprising a projector adapted to deliver a first beam of divergent light rays, means to convert said light rays to a rst beam of parallel light rays, a second projector adapted to deliver a second beam of divergent light rays, means to convert said light rays to a second beam of parallel light rays parallel to said rst beam, mirrors in the` path of each of said beams faced to direct the beams reflected therefrom toward each other, a multiprism mirror having alternate faces parallel respectively with said mirrors and in the path of the refiected beams, and means in the path of the last mentioned beams for correcting astigmatism.

6. An optical system comprising a projector adapted to deliver a first beam of divergent light rays, means to convert said light rays to a first beam of parallel light rays, a second projector adapted to deliver a second beam of divergent light rays, means to convert said light rays to a second beam of parallel light rays parallel to said first beam, mirrors in the path of each of said beams faced to direct the beams reflected therefrom toward each other, a multiprism mirror having alternate faces parallel respectively with said mirrors and in the path of the reflected beams, means in the path of the beams that have been reflected from the multiprism mirror to convert the parallel beams into convergent beams, and means in the path of the last mentioned beams for correcting astigmatism.

7. An optical system comprising a projector adapted to deliver a first beam of divergent light rays, means to convert said light rays to a first beam of parallel light rays, a second projector adapted to deliver a second beam of divergent light rays, means to convert said light rays to a second beam of parallel light rays parallel to said first beam, mirrors in the path of each of said beams and at an angle of 60 with their respective beams and faced to direct the reflected beams f toward each other, a multiprism mirror rhaving alternate` faces parallel respectively with said mirrors, said multiprism mirror being in the path of said reected beams, and means in the path of the ybeams reflected from Asaidy multiprism. mirror to convert the parallel beams into divergent beams.

- l 8. An optical 'system comprising a projector adapted yto deliver a first beam of divergentflight rays, means to convert said light rays to a first beam ofr parallel light rays, a second projector yadapted to deliver a second beam of kdivergent light rays, meansA to convert saidlight rays to a 'second ybeam of parallel light rays parallel to f said first beam, mirrors in the-path 'of each yof said beams and at an angle of 60 with theirrei spective beams and faced yto direct the reflected beams toward each other, al multiprism mirror having valternate faces parallel respectively with f said mirro;s,saidy multiprismmirror being in the path of said reectedbeams, means in the path of the beamsl reflected from said multiprism mirror to convert vtl'ie'parallel beams into convergent beams, and `means inftheipath of said'v convergent beams 'for correcting astigmatism.

r9.r An optical system comprising a projector Urors being intersected by a multiprism rmirror having alternate lraces parallel resjgiectivelyy with y adapted to deliver'a'rst beam of divergent'lightr rays, a second projector adaptedr to deliver a second beam of divergent light rays, spherical surface lenses in the'path of each of vsaid beams 'adaptedto convert said beams into parallel beams of parallel light rays, mirrors in the path ofk eachr of said parallel beams faced to reflect said beamsr toward each otherat an angley of 60 with said yparallel beams, a multiprism mirror having all ternate faces lparallel respectively with saidl mirrors, said multiprism mirror being in the path fof the reflected beams, a spherical lens in the path of the beams reflected from the multiprism mirror, said spherical lens being adapted to convertv they parallel beams into convergent f beams, and a cylindrical surface lens in the path y of the` lastnmentioned. beamsA for correcting astigmatism. y

10 yAn optical system jectcr adapted to deliver a first beam o divergent rlight' rays, al first lens adapted to convert ysaid light rays to a beam of parallel light rays, a rst mirror in'saidr parallel beam at an angle of 60"V thereto, a second projector adapted to deliver a second beam of divergentlight rays,y a second lens adapted to convert saidlight rays to a beam lof'parallel light rays, a second mirror in said parallel beam at `arifangle. of 60 thereto,r the beams reflected from said rst and second mirsaid mirrors, meansA to move said irst projector,

rst lens and first mirror laterally simultaneous-y ly, meansto move said second projector,second ylens andsecond mirror laterallyysimultaneously yand oppositely equidistantly to the direction of `movement vof said yiirstprojector, rst lens and f rst mirror,V and means to move said multiprism lmirror longitudinally. f l l ll. Iny the optical vsystem dei'ined'in claim 10.,

' means to move said first and second lenses andy said first and second mirrors longitudinally.

comprising a `first pro#y 

